Recovery of sugar precursors



scribed may be about to Patented Mar. 29, 1949 f umrao .s'r rEs PATENT OFFICE 2.465.947 anco'vaar or SUGAR raacoasoas Robert M. Boehm', Laurel, Miss., and Home E.

Hall, Lyle, Tenn., asslgnors to Masonite Corporation, Laurel, Miss., a corporation of Delaware No Drawing. Application March 31, 1944.

Serial No. 529,034

8 Claims. (01.127-40) This invention relates to separation of-noncellulosic carbohydrate anhydrides. or sugar pre cursors, i. e., materials from which sugars may 4 be formed, from solutions thereof in water, which may also contain other materials, such as sugars, tars, etc., in solution or suspension.

Two illustrative embodiments, of the invention will be described. First is the practice of the process upon wood liquors-derived from wood or woody lig'no-cellulose materials. which may be obtained, as by expression or washing, from fiber produced by subjecting wood chips to the hydrolyzing action of high pressure steam in a gun, such as described in U. S. Patent 1,824,221 to Mason, followed by explosive discharge from the gun. Such a liquor is described in U. S. Patent No. 2,224,135 to .Boehm.

In accordance with the description contained in the latter patent, lignocellulose material in the form of coarsely divided chips is subjected to saturated steam at pressures of about 600 to 1000 pounds per square inch and at corresponding temperatures (252 C. to 285 C.) in a gun for a short period of time. As a result of the hydrolysis treatment, the water soluble materials are increased and the liquor thus obtained from the hydrolysis treatment is used as the starting material in the present invention. V The wood liquor obtained as described contains materials produced from the hemicellulosic materials of the wood by the high pressure steam treatment, and which are soluble or dispersible in water. From these materials hexose and pentose sugars may be formed, and while such precursors of hexose and pentose may be in part polyuronides as well as polysans, they are herein referred to for convenience as hexosans and pentosans.

The liquor also-contains soluble or dispersed tars, some free sugars, acetic acid, formic acid, soluble or dispersed lignin or lignin degradation products,

astringents and other materials, the removal whereof is desirable in order to secure the sugar precursors in relatively pure form. The solid content of wood liquor obtained as above de- It is preferably concentrated to about %-50% of solid content before treatment according to this invention, and about 25% is preferable.

The invention can also be made use of in a second embodiment for recovery of sugar precursors such as hexosansby precipitation from water solutions containing same along with sugars such as pentoses and substantially free from other materials. By applying-the process of the present invention to such mixed solutions, the sugar precursors may be precipitated and removed and thus separated fromthe free sugars, such as pentoses and hexoses, which remain in solution.

The principal object of the invention consists in the provision of a process whereby the sugar precursors are precipitated so that they can be separated in relatively pure form by adding to the liquor certain oxygenated organic watermiscible liquid materials, which are of such na- -ture that the sugar precursors are precipitated because they are insoluble in the mixture of the added material with the water of the liquor.

A further'obiect is the .provision or a process whereby sugar precursors can be separated from free sugars. Additional objects of the invention will appear in connection with the further description The prkferred material to be admixed with the liquor to 4 partsof acetone with one part of isopropyl ether. ;While mixtures containing from about 3 to 8 parts ofacetone to one part of isopropyl ether may be used, the 4 to 1 ratio gives best results. Straight acetone may also be used when rapid precipitation is not important. Dioxane may also beused, or lower. aliphatic alcohols,

The precipitate of sugar precursors, which is white or light brown, can be separated from any materials remaining in solution, as by filtration.

Best results and highest purity of yield of sugar precursors are obtained by adjusting the pH of the solution to about 5.5. However, a range of pH from about 2-11 is permissible.

In one case, using the preferred precipitating agent material, namely 4 parts of acetone to 1 part .ofisopropyl ether, and the'prieferred ratio of the precipitating agent material to liquor, namely 4 parts thereof to 1 part of liquor, such liquor containing about of solid materials,

and having a pH of 5.5, the per cent recovery of sugar precursors by precipitation was 97.4, and the per cent purity of such recovered sugar precursors was 86.7.

The precipitation can be accelerated by the use of a minor proportion of an electrolyte, preferably an electrolytic salt, such as ab0ut1%-5% of aluminum sulfate on weight of solution.

The tars and other materials present in the wood liquor will remain in solution or suspension. Should some of these materials be carried down with the sugar precursor material, the separated precipitate may be washed with acetone or the like material for their removal.

e treated consists of a mixture of. about \I: v 3 V As already stated. solutions containing sugar precursors such as hexosans and also containing sugars such as pentose sugars and substantially free from other materials may be treated to separate the hexosans from the pentose sugars by making use ofthe present invention.

ter, and subjecting same to enzymatic hydrolysis by means of Aspergillus Niger enzyme material.

By such enzymatic hydrolysis, the pentosans are converted to pentose sugars. while the hexosaris remain substantially unchanged. and after the hydrolysis, both of these are in solution in the water. Apractically clear solution can be obtained. after filtering out the inoculated bran or the like used for introduction of the enzyme material, etc.

Upon the addition to such a solution of the 4 acetone-1 isopropyl ether mixture, or other ad- 'ditive material as already described, the hexosans are precipitated, and can be removed in relatively pure state. while the pentose sugars remain in solution. Thus the hexosan material is separated from the pentose sugar, and each may be utilized as desired.

The enzymatic hydrolysis treatment above referred to is not per se a part of this invention, being described and claimed in the copending application of Horace Hall and Lester L. Coleman, Serial No. 529,037, filed March 31, 194, now Patent Number 2,444,823, dated July 6, 1948.

We claim:

1.Process of preparing pentosans and hexosans from a fibrous lignocellulose material which comprises subjecting fibrous l ocellu'lose material in coarsely divided state to a hydrolyz ing ac-.

tion with saturated steam at pressure of approxi- -mately 600-1000 pounds per square inch and coring the precipitate from the solution.

2. Process as in claim 1, and in; which the precipitation of the pentosans and hexosans is accelerated by the addition of an electrolyte to the water solution of pentosans and hexosans.

3. Process as in claim 1, and in which the precipitation of the pentosans and hexosans is accelerated by addition to the watersolution of pentosans and hexosans of about 1% to 5% aluminum sulfate based on the wei ht of the solution.

4. Process as in claim 1, and in which the additiveprecipitating material is about 4 times the quantity of the water solution.

5. Processasinclaim Landinwhichthepfl of the pentosan and .hexosan water solution is adjusted to about 5.5 before addition of the precipitating material to the solution. I

6. Process of preparing pentosans andhexocomprises subjecting fibrous lig no-cellulose material in coarsely divided state to a hydroly zing action with saturated steam at pressure of approximately 600 to 1000 pounds per square inch and corresponding temperatures-whereby'a substantial part of said material is converted to water solubles in the form of pentosans and hexo-' sans, separating the pentosans and hexosans from the hydrolyzed ligno-ceilulose material by treating the hydrolyzed material with water, mixing with the pentosan and hexosan water solution a mixture containing 3 to 8 parts acetone and one .part isopropyl ether in quantities ranging from 2 to '7 times the quantity of the water solution to precipitate the pentosans and hexosans from the solution, and removing the precipitate irom the solution.

7. Process of preparing pentosans and hexosans from fibrous ligno-cellulose material which comprises subjecting fibrousligno-celiulose material in coarsely divided state. toa hydrolyzing action with saturated steam at pressure of approximately 600 to 1000 pounds per square inch and corresponding temperatures whereby a. substantial part of said material is converted to water solubles in the form of pentosans and hexosans, separating the pentosans and hexosans from I the hydrolyzed ligno-cellulose material by treat-,

ing the hydrolyzed material with water, mixing with the pentosan and hexos'an water solution sans from-fibrous ligno-cellulose material which comprises subjecting fibrous ligno-cellulose material in coarsely divided state to a hydrolyzing action with saturated steam at pressure of approximately 600 to 1000 pounds per square inch and corresponding temperatures whereby a substantial part of said material is converted to water solubles in the form of pentosans and hexosans, separating the pentosans and hexosans from the hydrolyzed ligno-cellulose material by treating the hydrolyzed material with water, mixing with the pentosan and hexosan water solution dioxane in quantities ranging from 2 to 7 times the quantity of the water solution to precipitate the pentosans and hexosans from the solution, and removing the precipitate from the solution.

- ROBERT M. BOEHM.

HORACE E. HALL.

REFERENCES CITED The following references are of record in the tile of thispatent:

UNITED STATES PATENTS Number Name Date 1,082,490 Berl Dec. 30, 1913 FOREIGN PATENTS 7 Number Country Date 376,372 Great Britain July 14, 1932 OTHER REFERENCES "Paper 1nd. and P. W.," February 1942, page 1150.

The Jour. of Ind. & Engr. Chem. (The Galactan of Larix Occidentalis). vol. 8, No.6, June 1916, pages 494 and 495.

Ind. 8: Eng. Chem., The Chem. of Wood," vol.

sans from fibrous ligno-cellulose material which 15 22. No. 4. pages 362and 363, April 1930. 

